Treasure Hunting Tractor! is a magazine story.
Percy is feeling very cheerful as he puffs along the seaside line, pulling a works train full of men and equipment. Percy steams past the pier and seaside amusements until he approaches a sandy bay. He rolls into a siding between the beach and a field. The workmen start to unload Percy's trucks.
Nearby, Terence is ploughing the field. He sees the workmen carrying spades down to the beach. Terence asks what they are doing and Percy, who likes nothing more than teasing Terence and the other engines, tells him they are digging for treasure. Terence wishes he could dig for treasure, too.
As Terence goes slowly up and down the field, he notices the men unloading timber from Percy's trucks and building a wall across the sand towards the sea. Terence is confused how this will help their quest for buried treasure. He is so confused that he does not watch where he is going. He pulls the plough over a rough corner of the field and almost falls into a ditch. His driver gets down to make sure the plough is not damaged. Terence tells his driver that he was looking to see if the men on the beach had found any treasure. Terence's driver tells him that the men are not looking for treasure, they are building a breakwater to stop the force of the waves washing the beach away. Then, Terence realises that Percy has tricked him. Suddenly, Terence's driver notices a small unusual object in the earth. He puts it in his pocket and goes back to driving Terence.
The next morning, when Percy arrives, he is surprised to see the men digging in Terence's field. Terence says they are digging for treasure and Percy does not believe him. But then, Terence's driver walks over to show Percy's driver something. Percy overhears Terence's driver say that Terence had found a fossil the previous day and they he contacted the museum who have sent experts to look for more. Terence proudly tells Percy what a fossil is and that the men are looking for huge creatures called dinosaurs that lived a long time ago.
When Terence's picture appears in the local newspaper with the headline "Treasure-hunting Tractor", Percy wishes he had not teased the clever tractor.